If you're on iTunes I think you can link your songs.

Google is your friend my man. I use this method, works 100%

Sorry, forgot to post the link

http://artoftheiphone.com/2009/01/19/how-to-create-an-iphone-ringtone-using-itunes/

Creating ringtones from music files.
Instruction for PC based ITunes:
Go to Itunes. Select song you want as ringtone. (You must have prchased song from ITunes or have as part of your own imported collection).
If it is a protected file (.4mp) then it will warn a against and prevent you creating a copy but read on.
Right click on song.
Select 'create AAC version'. This causes a copy of the song to be produced in the correct format. It will appear directly below the original.
Right click on the copy.
Select 'Get Info' and then select 'Options' tab.
Then modify 'Start' & 'Stop' times.
Your ringtone must be 30s or less. If you want the first 30 sec then the settings will be 0:00 and 30:00. (Format is important). (00:50 and 1:20 will select 50sec to 80 secs segment). After setting time sement;
Select OK.
On the copied version, right click and select 'create AAC Version'.
Another copy of the file will appear but time will be 30s long.
Right click on the 30s copy and select ' Show in Windows Explorer'. The selected file will be highlighted. Change the file type from .4Pa to .4pr (the r is Ringtone). Accept the changes. If you double click on the new file it will play the 30-sec  segment and also place the file in the Ringtone folder of Itunes.
You need to now go back and tidy up your master files. Remove the old 30s file (it will have an exclamation (!) mark beside it when you click on it.
Remove the copied file so that you are left only with you original files.
Please note you cannot change .4mp files (protected) to .4ma files as this would not be very fair to Apple, even though you have already paid for the file.
You will of course pay Apple to 'unprotect' these protected files? I do not know if there are any legal issues with carrying out the above so you make mods at your own risk. You also follow / implement the above at your own risk, as you are messing about with master files and copies but it works for me and is quite simple.
Regards,

Creating ringtones from music files.
Instruction for PC based ITunes:
Go to Itunes. Select song you want as ringtone. (You must have prchased song from ITunes or have as part of your own imported collection).
If it is a protected file (.4mp) then it will warn a against and prevent you creating a copy but read on.
Right click on song.
Select 'create AAC version'. This causes a copy of the song to be produced in the correct format. It will appear directly below the original.
Right click on the copy.
Select 'Get Info' and then select 'Options' tab.
Then modify 'Start' & 'Stop' times.
Your ringtone must be 30s or less. If you want the first 30 sec then the settings will be 0:00 and 30:00. (Format is important). (00:50 and 1:20 will select 50sec to 80 secs segment). After setting time sement;
Select OK.
On the copied version, right click and select 'create AAC Version'.
Another copy of the file will appear but time will be 30s long.
Right click on the 30s copy and select ' Show in Windows Explorer'. The selected file will be highlighted. Change the file type from .4Pa to .4pr (the r is Ringtone). Accept the changes. If you double click on the new file it will play the 30-sec  segment and also place the file in the Ringtone folder of Itunes.
You need to now go back and tidy up your master files. Remove the old 30s file (it will have an exclamation (!) mark beside it when you click on it.
Remove the copied file so that you are left only with you original files.
Please note you cannot change .4mp files (protected) to .4ma files as this would not be very fair to Apple, even though you have already paid for the file.
You will of course pay Apple to 'unprotect' these protected files? I do not know if there are any legal issues with carrying out the above so you make mods at your own risk. You also follow / implement the above at your own risk, as you are messing about with master files and copies but it works for me and is quite simple.
Regards,